Water quality improvement by implementation of Proposition O in the Los Angeles river watershed, California.

Proposition O was created to help the City of Los Angeles comply with the Total Maximum Daily Load (TMDL) requirements under the Clean Water Act. In this study, the effectiveness of the Proposition O projects in Los Angeles River watershed was examined to show whether it achieves the goal of meeting water quality standards. Our analysis shows the most effective single project will remove at most 2% of pollutant loads from Los Angeles River Watershed and will not achieve TMDL compliance, although several projects can make important contributions to achieve compliance. The ranking results show that the projects that treat the runoff from the largest drainage area have the greatest impact on the water quality of Los Angeles river.